This application is based on patent application No. 10-376679 (1998) filed Dec. 25, 1998 in Japan, the content of which is incorporated hereinto by reference.
1. Field of the Invention
The present invention relates to an ink printing method and an ink printing apparatus, and more particularly to the ink printing method and the ink printing apparatus which perform printing by using a processing liquid insolubilizing a colorant in an ink. The ink printing method and the ink printing apparatus of the present invention are applicable to equipment such as a printer, a copy machine, a facsimile machine or the like, which prints letters, images or the like on a printing medium such as paper or the like, and also used as a printing mechanism in such equipment.
2. Description of the Prior Art
An ink printing technique has an advantage of being essentially applicable to all types of printing medium. Owing also to this advantage, many of printers or the like utilizing the ink-jet printing technique are adapted to be able to use various types of printing medium such as plain paper, coated paper, transparency film for use in OHP, glossed paper and glossed film. On the other hand, there is a fact that the printers or the like have been desired to perform printing of higher quality and higher speed with the spread of the ink-jet type printers. More concretely, the reflection optical density (hereinafter referred to as xe2x80x9cODxe2x80x9d) at the same level as an electrophotographic method and high-speed fixing is required in printing characters such as black letters and so on. These circumstances are true for not only printing black letters but also printing full color images.
As an example of prior art trials to increase OD, there is proposed a configuration in which pigment ink is used for making much of printed quality of characters on plain paper. As another example, there is known a configuration in which dye ink and a processing liquid for insolubilizing the ink are used to perform printing.
As an example of such pigment ink for use in ink printing, there is disclosed one type of ink in which pigment is dispersed with AB, BAB type block polymers in Japanese Patent Application Laid-Open No.5-179183 (1993). There is disclosed another type of pigment ink in which pigment is dispersed with ABC type tri-block polymer in Japanese Patent Application Laid-Open No. 7-53841 (1995).
Further, there is known a self-dispersion type pigment ink in which a dispersant like the above block polymers is not used. As an example of this type ink, there is disclosed pigment ink in which carbon black as a pigment is dispersed by directly bonding a hydrophilic group to its surface in WO 96/18695 and WO 96/18696 related to International Patent Application.
In the systems using the pigment ink, however, coagulation of a pigment sometimes may occur on the surface of the printing medium depending on a type of the printing medium, which leads to a production of the image lacking uniformity in fixing a coloring material.
Further, when intensity of reaction causing the coagulation is relatively high, not only the non-uniform coagulation as described above is caused, but also a xe2x80x9ccrackxe2x80x9d, which is a portion lacking the coloring material, may be caused in the pigment fixed on a printing medium.
FIG. 1 is a schematic view showing a xe2x80x9ccrackxe2x80x9d phenomenon. As can be seen from the figure, a size of the xe2x80x9ccrackxe2x80x9d is relatively large and recognizable to the naked eye; thus, a presence of the xe2x80x9ccrackxe2x80x9d itself causing deterioration of the print quality. Further, an appearance of a printing medium ground at a portion of the xe2x80x9ccrackxe2x80x9d may cause decreasing of OD as a whole of the printed image.
Such xe2x80x9ccrackxe2x80x9d often occurs particularly in the printing medium, such as transparency film, having a resin coat layer formed on it which promotes acceptance of ink and is effective in high-speed fixing of the same. This is because the coagulation of the pigment on the resin coat layer depends on a substance contained in the resin. Anionic pigment ink rapidly coagulates especially when the resin coat layer contains a cationic substance.
Further, in printing systems using dye ink, when using the printing medium having the above coat layer formed thereon, a beading phenomenon sometimes may occur in which ink droplets form into a string like that of beads, as shown in FIG. 2, which may cause deterioration of print quality. This is because dye poorly wets the coat layer.
On the other hand, when increasing OD on the plain paper by using the pigment ink or both the dye ink and the processing liquid jointly, ink with lower penetrability is employed so that as much coloring material, such as pigment and so on, as possible will remain in a vicinity of the surface of the printing medium. Thus, when intending to increase OD on the plain paper, there arises a problem with fixing properties of ink.
An object of the present invention is to provide an ink printing method and an ink printing apparatus which make it possible to improve print quality, for example, OD level, and realize a high-speed fixing of ink in performing printing on various printing medium, particular, on a plain paper and a printing medium provided with a coat layer formed thereon (hereinafter referred to as a xe2x80x9cspecial printing mediumxe2x80x9d).
In a first aspect of the present invention, there is provided an ink printing method of applying ink containing at least a pigment as a coloring material onto a printing medium to perform printing, the method comprising the steps of:
providing a plurality of printing modes to be set corresponding to mode setting information, the plurality of printing modes including a printing mode for applying the ink and a processing liquid for promoting solidification of the coloring material in the ink onto the printing medium and a printing mode for applying no processing liquid but the ink onto the printing medium; and
selecting one mode corresponding to the mode setting information among the plurality of printing modes in accordance with a type of the printing medium to perform printing.
In a second aspect of the present invention, there is provided an ink printing apparatus for applying ink containing at least a pigment as a coloring material from a print head onto a printing medium to perform printing, the apparatus comprising:
mode setting means for setting a plurality of printing modes to be set corresponding to mode setting information, the plurality of printing modes including a printing mode for applying the ink and a processing liquid for promoting solidification of the coloring material in the ink onto the printing medium and a printing mode for applying no processing liquid but the ink onto the printing medium; and
print performing means for selecting one mode corresponding to the mode setting information among the plurality of printing modes in accordance with a type of the printing medium to perform printing.
According to the above configuration, it is possible to selectively carry out a mode for performing printing using both ink and the processing liquid jointly and a mode for performing printing not using the processing liquid but using ink alone. Thus, in the case of performing printing on a special printing medium provided with a coat layer formed thereon, for example, the mode using ink alone can be selected, and moreover, as the used ink, ink containing a mixture of the pigment and the dye may be selected to perform printing without causing deterioration in image quality, such as a crack on the coat layer, but printing with a high OD and a high-speed fixing. On the other hand, the mode is selected in which both ink and the processing liquid are used jointly as described above to perform printing in which an edge of the printed image is sharp without feathering and OD is high. Moreover, when the processing liquid is selected to have a high penetrability, in other words, to have a penetrability that agrees with a Ka value, an acetylenol content and surface tension shown in Table 1 described later, a high-speed fixing of ink can be also realized.
A term xe2x80x9cinsolubilizationxe2x80x9d used in the present specification does not mean just complete insolubilization, but it has a broader concept including an action promoting the insolubilization.